1. Field of the invention
This invention is directed to a connector assembly (or "sub") for use with various downhole tools and apparatuses. It is particularly useful with milling tools, taper taps, jars, die collars, overshots, spears, washpipe, fishing apparatuses, and junk baskets. This invention is also directed to the various combination tools and apparatuses which include the connector assembly.
2. Description of the prior art
Prior art connection assemblies are complex and often require a trip out of a wellbore for various phases of operation. Prior art tools and apparatuses, e.g. milling tools are complicated and also offer require multiple trips into and out of the hole to achieve their desired functions.
The prior art Baker Model C-1 milling tool has a connector assembly with a milling shoe or "burning shoe" and a stinger with an expandable grapple and a milling end. This miling tool is used, e.g., to remove a packer from a wellbore. In order to remove a packer using the Baker Model C-1 milling tool, the stinger with its grapple must be inserted through ("sting through") and beyond the packer. This usually requires some milling of the exterior of the packer by the burning shoe and of the interior of the packer by the milling end of the stinger, particularly if there is any obstruction inside the packer. After stinging through the packer, the grapple is expanded to hold the packer so that the milling tool and packer can be pulled out of the wellbore.
Many packers have extendable slips which extend from the packer to secure it in the wellbore. These slips must either retract back into the packer before its removal or they must be milled off prior to pulling the packer out of the hole.
Various problems are encountered when using the Baker Model C-1 milling tool. In various situations it is necessary to remove the tool from a packer, for example: When a stinger is accidentally stung into a packer (as when the depth of the packer has been misjudged); when an attempt is made to pull the packer and it hangs up in the wellbore; when the packer has not been properly milled; or when the slips either fail to retract or have not been properly milled). The grapple has to be contracted or unseated to relinquish its hold on the packer so that the tool can be removed from the packer. In order to re-set the grapple, the entire tool must then be removed from the wellbore, the packer must be re-set, and then be run back into the well-bore to the packer. This in an expensive procedure in an environment in which rig time can cost over $100,000 per day. A trip out and into a wellbore of 10,000 feet can take eight hours.
With prior art devices, the use of an overshot for removing pipe or other items from a hole can require multiple trips into and out of the hole. For example, a string with an overshot may be lowered into a hole to retrieve a piece of pipe. In pulling out of the hole once the pipe has been grappled by the overshot, the pipe may hang up or catch on some element in the wellbore. The overshot would have to be released and a milling tool inserted to mill away the obstruction. The milling tool would then have to be removed from the hole and the overshot would be re-inserted and another attempt made to grapple the pipe and pull it out.
There has been a long-felt need for a connection assembly which is simple, efficient, and easily repairable; and for a connection assembly for use with tools and apparatuses, e.g. a milling tool, which does not require multiple trips into and out of a wellbore to achieve its purposes.